Field of the Invention
The present invention relates to an automatic transmission for a vehicle. More particularly, the present invention relates to a planetary gear train of an automatic transmission for a vehicle having advantages of, by minimal complexity, realizing at least ten forward speeds, thereby improving power delivery performance and fuel consumption due to multi-stages, and improving driving stability of a vehicle by utilizing a low rotation speed of an engine.
Description of Related Art
Generally, in automatic transmission field, achieving more shift stages is a technology for maximizing fuel consumption and driving efficiency for which research has been conducted, and recent increases in oil prices are triggering stiff competition in enhancing fuel consumption of a vehicle.
In this sense, research on an engine has been undertaken to achieve weight reduction and to enhance fuel consumption by so-called downsizing, and research on an automatic transmission has been performed to simultaneously provide better drivability and fuel consumption by achieving more shift stages.
In order to achieve more shift stages for an automatic transmission, the number of parts, particularly the number of planetary gear sets is typically increased and installability, production cost, weight, and/or power flow efficiency according to total length of transmission is increased.
Therefore, in order to maximally enhance fuel consumption of an automatic transmission having more shift stages, it is important for better efficiency to be derived by a smaller number of parts.
In this respect, an eight-speed automatic transmission has been recently introduced, and a planetary gear train for an automatic transmission enabling more shift stages is continuously required.
However, the majority of general automatic transmissions having more than eight speeds include three to four planetary gear sets and five to six control elements (friction elements), in this case, total length is increased, which has drawbacks of deteriorating installability.
As a result, plural rows structure which planetary gear sets are on a planetary gear train has been adopted, or a dog clutch is applied in place of wet control elements. However, in this case, applicable structure is restricted and shift feel is deteriorated by applying the dog clutch.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.